Liquid crystal polymer film and method of making and use thereof

Abstract

The application discloses a liquid crystal polymer film, which is made of the following components by mass percentage: 50-70% of thermotropic liquid crystal molecule monomers, 25-35% of cross-linking agents, 1-10% of photo-initiators and 1-5% of photosensitive chiral agents. The liquid crystal polymer film is a flexible controllable and independent film forming device, has simple preparation process and convenient testing technology, and realizes multi-color and high saturation pattern through regulating and controlling the molecular arrangement and optical properties of the liquid crystal polymer film. The liquid crystal polymer film has excellent environmental stability and can keep stable performance under the change of humidity, pH and temperature, and is suitable for practical application in complex environment.

Description

Technical Field

[0001] This invention belongs to the field of liquid crystal preparation technology, specifically, it relates to a liquid crystal polymer film, its preparation method and application. Background Technology

[0002] With the advancement of technology and the acceleration of globalization, counterfeit and substandard products are rampant, seriously damaging consumer rights and brand reputation. Traditional anti-counterfeiting technologies, such as holograms and watermarks, have been gradually cracked and imitated, making it difficult to meet the ever-increasing anti-counterfeiting demands. Therefore, developing new, efficient, and difficult-to-replicate anti-counterfeiting technologies has become a current research hotspot. Liquid crystal polymer (LCP) films, due to their unique optical properties and tunable molecular arrangement, show great application potential in the field of anti-counterfeiting. By controlling the molecular arrangement of LCP films, precise control over the polarization and wavelength of light can be achieved, resulting in a variety of patterns and optical effects. These patterns and effects are highly complex and unique, making them difficult to replicate and imitate, providing new ideas for anti-counterfeiting technology. Although laser processing for fabricating patterned photonic crystal films (CN118732327A) has high precision, the laser processing process relies on the high-precision positioning of photolithography equipment and complex optical systems, which not only increases equipment costs and maintenance difficulty but also limits the freedom of processing size and pattern design. Furthermore, while inkjet printing technology (CN102161284A) offers high flexibility and enables the rapid fabrication of complex patterns, it imposes stringent requirements on the physical properties of precursor materials. This significantly limits the range of materials that can be used in printing, preventing the direct application of many high-performance functional materials with unsuitable physical properties. Therefore, developing a highly flexible, simple, and widely applicable method for preparing editable color-patterned liquid crystal polymer films has significant research value and application prospects, offering broader possibilities for the application of photonic crystals in optical devices, display technology, and anti-counterfeiting fields.

[0003] Laser processing relies on high-precision photolithography equipment, which is costly and limits the freedom of pattern design. Inkjet printing has stringent requirements for precursor materials, limiting the application range of high-performance materials. Summary of the Invention

[0004] The purpose of this invention is to provide a liquid crystal polymer film.

[0005] Another object of the present invention is to provide a method for preparing the liquid crystal polymer film.

[0006] Another object of the present invention is to provide an application of the liquid crystal polymer film in the preparation of optical devices, display devices, and anti-counterfeiting products.

[0007] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0008] In a first aspect, the present invention provides a liquid crystal polymer film made of the following components by mass percentage: 50-70% thermotropic liquid crystal monomer, 25-35% crosslinking agent, 1-10% photoinitiator, and 1-5% photosensitive chiral agent.

[0009] The thermotropic liquid crystal monomers are selected from 1,4-bis-[4-(3-acryloyloxypropoxy)benzoyloxy]-2-methylbenzene (RM257), 1,4-bis-[4-(6-acryloyloxyhexyloxy)benzoyloxy]-2-methylbenzene (RM82), 4-[[6-[(1-oxo-2-propenyl)oxy]hexyl]oxy]benzoic acid 4-methoxyphenyl ester (RM105), 4-cyanophenyl 4-((6- At least one of (acryloyloxy)hexyl)oxy)benzoate (RM23), 2-methyl-1,4-phenylenebis(4'-(((4'-(acryloyloxy)butoxy)carbonyl)oxy)benzoate (LC242), and 6-[[[4-[(1-oxo-2-propen-1-yl)oxy]butoxy]carbonyl]oxy]-2-naphthoic acid 2,2'-[2-(methoxycarbonyl)-1,4-phenylene] ester (LC1057).

[0010] The crosslinking agent is selected from trimethylolpropane triacrylate (TMPTA).

[0011] The photoinitiator is selected from at least one of 1-hydroxycyclohexylphenyl ketone (Irgacure 184), 2,2-dimethoxy-phenylacetophenone (Irgacure 651), and 2-methyl-1-(4-methylthiophenyl)-2-morpholino-1-propanone (Irgacure 907).

[0012] The photosensitive chiral agent has one of the following structures:

[0013]

[0014] The liquid crystal polymer film is made of the following components by mass percentage: 60-65% thermotropic liquid crystal monomer, 30-35% crosslinking agent, 2.5-5% photoinitiator, and 2-3% photosensitive chiral agent.

[0015] The liquid crystal polymer film is made of the following components by mass percentage: 65% thermotropic liquid crystal monomer, 30% crosslinking agent, 3% photoinitiator, and 2% photosensitive chiral agent.

[0016] The liquid crystal polymer film is made of the following components in weight percentage: 60% thermotropic liquid crystal monomer, 35% crosslinking agent, 2.5% photoinitiator, and 2.5% photosensitive chiral agent.

[0017] The liquid crystal polymer film is made of the following components by mass percentage: 60% thermotropic liquid crystal monomer, 32% crosslinking agent, 5% photoinitiator, and 3% photosensitive chiral agent.

[0018] A second aspect of the present invention provides a method for preparing the liquid crystal polymer film, comprising the following steps:

[0019] A homogeneous system is formed by mixing thermotropic liquid crystal polymer monomers, crosslinking agents, photoinitiators, and photosensitive chiral agents. The homogeneous system is then encapsulated in a liquid crystal cell. The pattern color is controlled by visible light irradiation, and then polymerized into a film by ultraviolet light irradiation to obtain the liquid crystal polymer film.

[0020] The thickness of the liquid crystal cell is 20 to 50 micrometers (preferably 30 micrometers, 40 micrometers, or 50 micrometers).

[0021] The substrate material of the liquid crystal cell is selected from glass and polymethyl methacrylate (PMMA).

[0022] The visible light wavelength is 405~600 nm (preferably 450, 425, 405 nm), and the intensity is 0.1~20 mW / cm². -2 (Preferred values ​​are 5, 8, and 4 mW cm) -2 ).

[0023] The ultraviolet light has a wavelength of 300-400 nanometers (preferably 365 nanometers) and an intensity of 0.1-20 mW / cm². -2 (Preferred values ​​are 2, 3, or 4 mW cm) -2 ).

[0024] A third aspect of the present invention provides an application of the liquid crystal polymer film in the preparation of optical devices, display devices, and anti-counterfeiting products (such as information anti-counterfeiting labels).

[0025] By adopting the above technical solution, the present invention has the following advantages and beneficial effects:

[0026] The liquid crystal polymer film of the present invention can achieve arbitrary customization of structural color in the visible light region (450-750 nm) under different visible light doses of irradiation, thus meeting the customization needs of different users.

[0027] The liquid crystal polymer film of this invention is a flexible, controllable, and independently formed device with a simple fabrication process and convenient testing technology. By controlling the molecular arrangement and optical properties of the liquid crystal polymer film, multi-color (purple, blue, green, yellow, and red) patterns can be achieved. The liquid crystal polymer film of this invention exhibits excellent environmental stability, maintaining stable performance under changes in water, alkaline solutions, and temperature, making it suitable for practical applications in complex environments.

[0028] This invention proposes a highly flexible, simple, and widely applicable method for preparing editable color-patterned liquid crystal polymer films. This method not only simplifies the process but also allows for customized design of pattern colors. Furthermore, the prepared films exhibit excellent environmental stability, maintaining superior performance stability under varying environmental conditions such as humidity, pH, and temperature, further expanding their practical application potential in optical devices, display technologies, and anti-counterfeiting in complex environments. Attached Figure Description

[0029] Figure 1 This is a schematic diagram illustrating the design principle of color pattern preparation and anti-counterfeiting application of liquid crystal polymer films.

[0030] Figure 2 This is a schematic diagram of the liquid crystal polymer film prepared in Example 1.

[0031] Figure 3 This is a schematic diagram of the liquid crystal polymer film prepared in Example 2.

[0032] Figure 4 This is a schematic diagram of the liquid crystal polymer film prepared in Example 3.

[0033] Figure 5 This is a schematic diagram of the liquid crystal polymer film prepared in Comparative Example 1. Detailed Implementation

[0034] To more clearly illustrate the present invention, the following description, in conjunction with preferred embodiments, further clarifies the invention. Those skilled in the art should understand that the specific descriptions below are illustrative rather than restrictive, and should not be construed as limiting the scope of protection of the present invention.

[0035] Figure 1 This is a schematic diagram of the color pattern preparation of liquid crystal polymer film and its anti-counterfeiting application design principle. In this diagram, 101 is the liquid crystal cell substrate, and 201 is the spiral structure formed by all the raw materials of the liquid crystal polymer film in the liquid crystal cell. The height is 20~50 micrometers and the color is the structural color in the visible light region (450-750 nm).

[0036] 301 is visible light, with a wavelength of 405-480 nanometers and an intensity of 0.1-20 mW / cm². -2 .

[0037] 401 is visible light, with a wavelength of 480-600 nanometers and an intensity of 0.1-20 mW / cm². -2 .

[0038] 501 is an optical photomask; the black area represents the opaque region.

[0039] 601 is a spiral structure formed by all the raw materials of the liquid crystal polymer film in the liquid crystal cell, with a height of 20-50 micrometers and a color in the visible light region (420-750 nm), which is different from the structural color described in 201.

[0040] 701 is ultraviolet light, with a wavelength of 300-400 nanometers and an intensity of 0.1-20 mW / cm². -2 .

[0041] 801 is a thin film formed by polymerization after being irradiated with ultraviolet light.

[0042] All components of the liquid crystal polymer film are encapsulated within a liquid crystal cell. Initially purple, upon irradiation with 301 light, the structure of the light-transmitting region changes, exhibiting different colors. This color sequentially transitions to blue, green, yellow, and red with increasing irradiation time, and this process can be reversibly reversed back to the initial purple color by irradiation with 401 light. Further irradiation with 701 light causes all components of the liquid crystal polymer film to polymerize, forming the corresponding film.

[0043] Example 1

[0044] A method for preparing a liquid crystal polymer film includes the following steps:

[0045] A homogeneous system was formed by uniformly mixing thermotropic liquid crystal monomer RM257 (65% by mass), crosslinking agent TMPTA (30% by mass), photoinitiator Irgacure 184 (3% by mass), and photosensitive chiral agent (2% by mass). This homogeneous system was then encapsulated in a 30-micrometer-thick liquid crystal cell with a glass substrate. The entire material system exhibited a purple structural color when exposed to visible light at a wavelength of 450 nm (intensity 5 mW cm⁻¹). -2 A mask with a dragonfly pattern was vertically illuminated (i.e., the dragonfly pattern area was transparent, while the non-pattern area was opaque). The middle area was illuminated for 23 seconds, and the two side areas were illuminated for 18 seconds, ultimately achieving a red and orange colored dragonfly pattern on a blue substrate. Figure 2 As shown, Figure 2 This is a schematic diagram of the liquid crystal polymer film prepared in Example 1. Subsequently, ultraviolet light with a wavelength of 365 nm (intensity 2 mW cm⁻¹) was used. -2Irradiation for 10 minutes allows the system to polymerize into a film, resulting in a colored liquid crystal polymer film with clear patterns and vibrant colors. Even after heating at 60℃ for 10 hours, the pattern remains stable and is suitable for information anti-counterfeiting labels.

[0046] The structure of the photosensitive chiral agent is shown below:

[0047]

[0048] Example 2

[0049] A method for preparing a liquid crystal polymer film includes the following steps:

[0050] A homogeneous system was formed by uniformly mixing thermotropic liquid crystal monomers RM82 (40% by mass) and LC242 (20% by mass), crosslinking agent TMPTA (35% by mass), photoinitiator Irgacure 184 (2.5% by mass), and photosensitive chiral agent (2.5% by mass). This homogeneous system was then encapsulated in a 40-micrometer-thick liquid crystal cell substrate made of PMMA. The entire material system exhibited a purple structural color when exposed to visible light at a wavelength of 425 nm (intensity 8 mW cm⁻¹). -2 A mask with a rectangular pattern was vertically illuminated (i.e., the rectangular patterned area was transparent, while the non-patterned area was opaque). The left area was illuminated for 5 seconds, the middle area for 12 seconds, and the right area for 20 seconds, ultimately achieving a blue, green, and red colored rectangular pattern. Figure 3 As shown, Figure 3 This is a schematic diagram of the liquid crystal polymer film prepared in Example 2. Subsequently, ultraviolet light with a wavelength of 365 nm (intensity 4 mW cm⁻¹) was used. -2 Irradiation for 8 minutes allows the system to polymerize into a film. The film has high pattern resolution, and the pattern remains stable even after immersion in a sodium hydroxide aqueous solution at pH 10 for 10 hours, making it suitable for display devices in complex environments.

[0051] The structure of the photosensitive chiral agent is shown below:

[0052]

[0053] Example 3

[0054] A method for preparing a liquid crystal polymer film includes the following steps:

[0055] A homogeneous system was formed by uniformly mixing thermotropic liquid crystal monomers RM105 (35% by mass) and RM23 (25% by mass), crosslinking agent TMPTA (32% by mass), photoinitiator Irgacure 907 (5% by mass), and photosensitive chiral agent (3% by mass). This homogeneous system was then encapsulated in a 50-micrometer-thick liquid crystal cell, with the cell substrate being glass. The entire material system exhibited a purple structural color when exposed to visible light at a wavelength of 405 nm (intensity 4 mW cm⁻¹). -2 A photomask with a teacup pattern was vertically illuminated (i.e., the teacup pattern area was transparent, while the non-pattern area was opaque). The upper area was illuminated for 19 seconds, and the lower area was illuminated for 10 seconds, ultimately achieving an orange and green colored teacup pattern on a blue substrate. Figure 4 As shown, Figure 4 This is a schematic diagram of the liquid crystal polymer film prepared in Example 3. Subsequently, ultraviolet light with a wavelength of 365 nm (intensity 3 mW cm⁻¹) was used. -2 Irradiation for 10 minutes allows the system to polymerize into a film, resulting in a liquid crystal polymer film with a full-color pattern. After immersion in water for 10 hours, the pattern remains stable and is suitable for display and optical anti-counterfeiting applications.

[0056] The structure of the photosensitive chiral agent is shown below:

[0057]

[0058] Comparative Example 1

[0059] A method for preparing a liquid crystal polymer film includes the following steps:

[0060] A homogeneous system was formed by uniformly mixing thermotropic liquid crystal monomer RM257 (65% by mass), crosslinking agent TMPTA (30% by mass), photoinitiator Irgacure 184 (3% by mass), and commercial chiral agent R5011 (2% by mass). This homogeneous system was then encapsulated in a 30-micrometer-thick liquid crystal cell with a glass substrate. The entire material system exhibited a green structural color when exposed to visible light at a wavelength of 450 nm (intensity 5 mW cm⁻¹). -2 When a mask with a dragonfly pattern is vertically illuminated (i.e., the dragonfly pattern area is transparent while the non-pattern area is opaque), the central area is illuminated for 23 seconds and the two side areas are illuminated for 18 seconds. In the end, it still maintains a uniform green color and no corresponding colored pattern is produced. Figure 5 As shown, Figure 5 This is a schematic diagram of the liquid crystal polymer film prepared in Comparative Example 1. Subsequently, ultraviolet light with a wavelength of 365 nm (intensity of 2 mW / cm²) was used. -2Irradiate for 10 minutes to allow the system to polymerize into a film, resulting in a green liquid crystal polymer film.

[0061] The structure of the commercial chiral agent R5011 is shown below:

[0062]

[0063] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some modifications or alterations to the above-described technical content to create equivalent embodiments without departing from the scope of the present invention. Any simple modifications, equivalent changes, and alterations made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.

Claims

1. A method of producing a liquid crystalline polymer film, characterized by, The method comprises the following steps: The thermotropic liquid crystal molecule monomer, the crosslinking agent, the photoinitiator and the photosensitive chiral agent are mixed to form a uniform system, the uniform system is packaged in a liquid crystal cell, the color of a control pattern is controlled by visible light irradiation, and then the liquid crystal polymer film is obtained by polymerization into a film through ultraviolet light irradiation; The liquid crystal polymer film is prepared from the following components in mass percentage: 50-70% of the thermotropic liquid crystal molecule monomer, 25-35% of the crosslinking agent, 1-10% of the photoinitiator and 1-5% of the photosensitive chiral agent; The thermotropic liquid crystal molecule monomer is at least one selected from 1,4-bis-[4-(3-acryloyloxypropoxy)benzoyloxy]-2-methylbenzene, 1,4-bis-[4-(6-acryloyloxyhexyloxy)benzoyloxy]-2-methylbenzene, 4-[[6-[(1-oxo-2-propenyl)oxy]hexyl]oxy]benzoic acid 4-methoxyphenyl ester, 4-cyanophenyl 4-((6-(acryloyloxy)hexyl)oxy)benzoate, 2-methyl-1,4-phenylene bis(4'-(((4'-(acryloyloxy)butoxy)carbonyl)oxy)benzoate), and 6-[[[4-[(1-oxo-2-propen-1-yl)oxy]butoxy]carbonyl]oxy]-2-naphthalenecarboxylic acid 2,2'-[2-(methoxycarbonyl)-1,4-phenylene] ester; The crosslinking agent is selected from trimethylolpropane triacrylate; The photoinitiator is at least one selected from 1-hydroxycyclohexyl phenyl ketone, 2,2-dimethoxy-phenyl phenyl ethanone and 2-methyl-1-(4-methylthiophenyl)-2-morpholino-1-propanone; The photosensitive chiral agent has one of the following structures:

2. The method for preparing a liquid crystal polymer film according to claim 1, characterized in that, The thickness of the liquid crystal cell is 20-50 microns; The substrate material of the liquid crystal cell is selected from glass and polymethyl methacrylate (PMMA).

3. The method for preparing a liquid crystal polymer film according to claim 1, characterized in that, The wave band of the visible light is 405-600 nm, and the intensity is 0.1-20 mW cm -2 .

4. The method for preparing a liquid crystal polymer film according to claim 1, characterized in that, The ultraviolet light has a wavelength band of 300-400 nm and an intensity of 0.1-20 mW cm -2 .

5. The method for preparing a liquid crystal polymer film according to claim 1, characterized in that, The liquid crystal polymer film is prepared from the following components in mass percentage: 60-65% of the thermotropic liquid crystal molecule monomer, 30-35% of the crosslinking agent, 2.5-5% of the photoinitiator and 2-3% of the photosensitive chiral agent.

6. The method for preparing a liquid crystal polymer film according to claim 2, characterized in that, The liquid crystal polymer film is prepared from the following components in mass percentage: 65% of the thermotropic liquid crystal molecule monomer, 30% of the crosslinking agent, 3% of the photoinitiator and 2% of the photosensitive chiral agent.

7. The method for preparing a liquid crystal polymer film according to claim 2, characterized in that, The liquid crystal polymer film is prepared from the following components in mass percentage: 60% of the thermotropic liquid crystal molecule monomer, 35% of the crosslinking agent, 2.5% of the photoinitiator and 2.5% of the photosensitive chiral agent.

8. The method for preparing a liquid crystal polymer film according to claim 2, characterized in that, The liquid crystal polymer film is prepared from the following components in mass percentage: 60% of the thermotropic liquid crystal molecule monomer, 32% of the crosslinking agent, 5% of the photoinitiator and 3% of the photosensitive chiral agent.

9. The liquid crystal polymer film prepared by the method of any one of claims 1 to 8 is applied to the preparation of optical devices, display devices and anti-counterfeiting products.

Images